Method of sealing the mouths of bags



May 23, 1944.

s. HOWARD 2,349,732

METHOD oF sEALNG THE MoUTHs oF BAGS Filed May 15. 1940 .N INVENTOR l SM R. ALW/al QLMcLlLQ ATTORNEY Patented-May 23, 1944 METHOD OF SEALING THE MOUTHS 0F BAGS Stanley Pneumatic Scale Corporation,

R. Howard, Milton, Mass., assigner to Limited, Quincy,

Mass., a corporation of Massachusetts Application May 15, 1940, Serial No. 335,279

7 Claims.

This invention relates to a method of sealing the mouth of a bag or other container.

The invention has for an object to provide a novel method of sealing the mouth of a container and particularly a bag to provide the same with an efficient and superior moisture-proof seal for have been heretofore experienced, may be avoided and a package possessing improved moistureproof characteristics obtained.

With these general objects in view and such others as may hereinafter appear, the invention consists in the method of sealing the container and in the various steps thereof hereinafter described and particularly defined in the claims at the end of this specification.

In the drawing Fig. 1 is a perspective view diagrammat/ically illustrating the preferred form of the apparatus which may be employed in producing the novel sealed package by the present method; Fig. 2 is a cross-sectional view through the folded portions of the mouth of the bag before the exterior seal has been applied; Fig. 3 is a similar view showing the manner in which the exterior seal is applied by the apparatus illustrated in Fig. 1; Fig. 4 is a similar view showing the folded mouth of the bag completely enclosed by the seal; and Fig. 5 is a perspective view illustrating a step in a modification of the method shown in Fig. 1.

The present method is particularly directed to y the production of an eiiicient closure for the mouth of the wax or parafiin coated paper liner to produce a moisture-proof package. Heretofore, various methods have been employed in proriding a sealed top closure for such liner bags. One method contemplated is pressing the side walls of the mouth of the liner bag together while applying heat in order to melt the wax or paraffin coating to thereby effect adhesion of the opposing interior side walls of the mouth of the bag, thus producing the seal, upon subsequent cooling and congealing of the molten wax or paraffin.

Another method contemplated is the provision of awax free mouth portion for the liner bag and the adhesive sealing of such portion by glue or other adhesive. The present method of producing a sealed package and of sealing the mouth of the liner comprises an improvement upon such prior methods. In the first method above described, where the opposing sides of the mouth of the wax impregnated or coated bag are fused or melted together by the application of heat and pressure, it was found that during the heat sealing operation, a substantial portion of the parafn or other wax melted and ran or was diffused to such an extent as to leave portions of the mouth substantially free from wax. This condition produced a defective seal and permitted air and moisture to enter the container at the wax free portions, thus detracting from the moistureproof characteristics of the liner bag. The second method of course has been likewise objectionable by reason of the wax free, portions of the mouth of the liner bag and thetendency for moisture and air to permeate therethrough into the liner bag.

In accordance with the present invention, the mouth of the liner bag of paraffin paper or equivalent material may be provided with a closure of any usual or preferred form and the folded mouth portion is provided with an exterior coating of melted wax or paraffin so as to enclose the mouth portion and so that upon cooling, the mouth of the bag is provided with a cap of the waxy substance to produce a seal impervious to air, moisture or vermin. The present method found use in perfecting the seal of liner bags produced in accordance with the prior methods, as where the mouth of the bag has been adhesively sealed, as above described, the exterior surface of the mouth portion originally wax free, may be provided with a coating of wax to produce an entirely moisture-proof liner, and where the wax has been dissipated by the application of heat and pressure in the heat sealing operation, as above described, the wax thus dissipated may be replaced by the application of a new coating of melted wax to the exterior of the folded mouth portion thus formed.

Referring now to the drawing, I0 represents an open mouthed bag herein illustrated as forming the inner liner for a carton I2 having the usual top closing flaps I4, I6. The liner lll may be made up in rectangular formation in any usual or preferred manner to fit into the carton and may be made of a length sufficient to extend a substantial distance above the top score line of the carton, when assembled therewith. The liner may be formed from any of the commercial moisture-proof papers now upon the market, such as a paraffin or wax coated paper, and as illustrated, the upper edge or mouth portion i8 of the liner is preferably wax free to permit this portion to readily absorb the adhesive subsequently applied.`

In some instances, the wax free edge may be produced by removing the wax by the application of heat and pressure during the operation of forming the bag as illustrated in Fig. 5, or the bag making material may be supplied with wax free edges by the manufacturer as shown in Fig. 1.

As illustrated in Fig. l, the open mouthed liner is provided with a top closure preferably comprising an elongated fold 20 which may be formed by inserting blade members 22 into the interior of the bag and then spreading them apart thereby drawing the opposed sides 24, 26 of the bag together, as shown, to form a vertically extended elongated fold. Thereafter, at the next station of operation, as diagrammatically illustrated inv Fig. l, the interior surfaces of the mouth portion may be provided with a coating of adhesive 28 which may be applied by inserting an elongated transfer member 30, previously supplied with glue or other adhesive into the bag adjacent the mouth portion and then pressing the opposed side against the transfer member while it is being withdrawn to wipe the adhesive from the latter against the interior of the mouth portion lof the liner. The adhesively coated portions are then pressed firmly together by presser members 32, 34, to initially seal the mouth portion of the liner.

As hereinbefore stated, such initial sealing operation may also be accomplished by heat sealing the mouth portion of the bag after the folded top closure has been formed and in such case, the entire bag including the mouth portion being of wax or parafin coated paper and, as shown in the modification illustrated in Fig. 5, in such instances, heat sealing presser members 313, 35 may be employed, at least one of which may comprise an electrically heated element, as indicated. The top fold of the top closure may take various forms, such as a bellows fold, produced by tucking in the ends of the mouth portion and then pressing together the opposing sides. Furthermore, in some instances, it may be desirable to dispense with any initial sealing operation, merely folding the top of the bag to form a closure as above described.

In accordance with the present invention, the folded top closure thus formed (either initially sealed as above described or merely folded), is provided with an exterior coating of paraffin or other wax-like substance to seal the same in a manner such as to effect simultaneous application of the wax like substance to the sides oi? the closure and over the top edges thereof, and the illustrated structure for performing this operation comprises a pair of driven transfer rollers 40,42 which are supplied with a melted wax such as parailln 44 from a supply tank 4B. The melted wax is'drawn up from the tank by a pump 48 and is continuously fed through pipes 50, 52 onto the rollers 40, 42. The surplus wax is permitted to drain into the receptacles 54, 56 and thence through drain pipes 58. 60 back into the supply tank 46.l Scrapers 62, arranged to engage and embrace the edge of the rollers, operate to wipe off the surplus wax from the rollers, and to maintain a uniform film of wax thereon to be applied to the previously formed closure. The wax is maintained in its melted state in any usual manner, such as by an electrically heated plate 64 adapted to maintain the wax at a uniform state of liquidity. In practice, the top closure previously formed, is passed between the rollers, as shown, to transfer the parailin in its liquid state simultaneously onto the sides of the closure and over the top edges, as clearly illustrated in Fig. 3,

.materiaL and while it is preferred whereupon the waxy substance is permitted to cool, to produce a continuous seal 45, as shown in Fig. 4.

In the production of the completed package. the sealed closure may then be folded down on top of the package by suitable folding mechanism 68, and thereafter the top flaps I4, I8 of the carton are folded over and adhesively sealed in any usual or preferred manner. As illustrated, the forwardfend flap I4 is first folded over by a stationary rail 1x0, during the movement of the container thereby, and thereafter the trailing end flap l 4 is folded over by a movable folder 12. 'I'he side flaps i6 are rollers 14 whereupon the side aps may be folded over on top of the container by stationary rails 76, 'I8 in the usual manner. Thereafter pressure is applied to the top of the carton to firmly set the adhesively sealed flaps to produce the completed package.

The terms wax or wax-like as used herein are intended to dene and include any suitable wax..

parafiin or other suitable moisture-proof sealing to utilize the rollers as described for applying the wax to the closure, it will be understood that the wax may be applied in other ways if found advantageous, to effect simultaneous application of the molten wax to the sides and over the top edges of the closure, as described.

While the preferred apparatus for practicing the in'vention has bee'n herein illustrated and described, it will be understood that other apparatus may be used.

Having thus described the invention, what is claimed is:

1. The method of sealing an open-mouthed container which comprises: collapsing the mouth of said container by bringing together the side portions thereof adjacent said mouth so as to form a substantially vertical closure, and simultaneously applying a moisture-proof sealing substance to the exterior surfaces of both of said vertical collapsed side portions along said mouth and on the upper edges of said vertical side portions prior to folding the closure, whereby to form a continuous sealing cap adhering to said vertical side portions and top edges of said vertical side portions to provi e a substantially air-tight and moisture-proof seal for said mouth.

2. The method of sealing an open-mouthed container which comprises: dlstending the mouth of said container to inwardly collapse the side portions thereof adjacent said mouth to form a substantially vertical closure, and simultaneously applying a moisture-proof sealing substance to the exterior surfaces of both of said vertical collapsed side portions along said mouth and on the upper edges of said vertical side portions prior to folding the closure, whereby to form a continuous sealing cap adhering to said vertical side portions and top edges of said vertical side portions to provide a substantially air-tight and moisture-proof seal for said mouth.

3. The method of sealing an open-mouthed container which comprises: dlstending the mouth of said container to inwardly collapse the side portions thereof adjacent said mouth to form a substantially vertical closure, and applying molten wax simultaneously to the exterior surfaces of both of said vertical collapsed side portions along said mouth and on the upper edges of said vertical side portions prior to folding the closure, whereby to form a continuous wax cap adhering to said vertical side portions and top edges of then supplied with adhesive bysaid vertical side portions to provide a substantially air-tight and moisture-proof seal for said mouth.

4. The method of sealing an open-mouthed bag having the portions to be sealed substantially wax-free whichcomprises, folding together the sides of the mouth portion of the bag to form a substantially vertical closure, applying adhesive to a substantial area of the interior surface of the mouth portion at the wax free areas prior to folding the closure, pressing together the sides of the mouth portion to which the adhesive has been applied to adhesively seal the mouth portion, and then simultaneously applying a melted wax-like substance to the exterior surfaces o! both of the vertical sides at said mouth portion and on the top edges of said sides prior to folding the closure, whereby to form a cap covering said mouth portion and adjacent side portions to provide a substantially air-tight and moisture-proof seal upon cooling and hardening of the wax-like substance.

5. The method of sealing an open-mouthed l bag which comprises: folding together the sides of the mouth portion of the bag to form a substantially vertical closure, and passing said mouth portion with the sides thereof in a substantially vertical position through a supply of a moistureproof sealing substance to transfer said substance simultaneously onto the exterior surfaces of said sides adjacent said mouth portion and onto the top edges of said sides so that said substance also overlies said mouth portion, whereby to form a continuous cap of the sealing substance over said mouth portion and adjacent vertical side portions to provide a substantially air-tight and moistureproof seal for said bag.

6. The method of sealing an open-mouthedV bag treated with a, waxy substance which comprises:l folding together the sides of the mouth portion of the bag to form a substantially vertical closure, pressing together and heat sealing the mouth portion of the bag to effect adhesion thereof, and applying a melted waxy substance simultaneously to the exterior surfaces of the vertical sides contiguous to said mouth portion and on the top edges of said sides while the closure remains in a vertical unfolded condition, whereby to replace the wax which was dissipated by said heat sealing operation and to form a con-i tinuous cap over said mouth portion to produce a substantially air-tight and moisture-proof seaP for said closure upon cooling and hardening of the waxy substance.

'1. The method of sealing an open-mouthed bag treated with va waxy substance which comprises: folding together the sides of the mouth portion of the bag to form a substantially vertical closure portion, applying heat and pressure to the closure portion to soften the waxy substance and to eiect adhesion of the mouth portions of the bag, and simultaneously applying a. melted wax-like substance to the exterior side surfaces and on the top edges of the closure while the closure remains in a vertical unfolded condition, whereby to form a sealing cap for said closure to provide a substantially air-tight and moistureproof seal upon cooling and hardening of the wax-like substance.

STANLEY R. HQWARD. 

